Numerous medical procedures require access to an internal portion of a person's body (either directly or indirectly). Typically, the less intrusive the access, the better. As a result, many such procedures are performed with one or more tools at the remote end of an elongate flexible member which are inserted into the patient's body and operated remotely. For example, in order to obtain a sample of esophagus tissue, a practitioner inserts an endoscope into the patient's esophagus and then feeds a cable (made of coiled stainless steel wire) through the endoscope and into proximity with the patient's esophagus. Biopsy jaws are connected to the remote end of the cable and are operable to capture a tissue sample. The jaws are actuated by axial movement of a wire nested within the cable.
As can be appreciated by anyone who has attempted to unlock a car door with a coat hanger, it is one thing to get the coat hanger into proximity with the door latch, and it is quite another to hook the latch and pull it open. The same can be said for operation of an endoscopic probe of the type described above, particularly when one recognizes that the probe must be inserted through a tube and yet perform a task on a body part that is typically radially displaced from the axis of the tube. In other words, the endoscope gets the biopsy jaws down into the patient's esophagus, but the tissue may be off to the side. One approach to overcome this problem has been to deflect the endoscope to aim the biopsy jaws in the desired direction. However, the size of the endoscope and/or anatomical constraints place significant limitations on this practice.
U.S. Pat. No. 4,945,920 discloses a device having a radially extending tip which can be maneuvered relative to a patient by rotating the entire device within the endoscope. However, this device is difficult to operate because rotation of the entire device can cause "twist" to accumulate, and friction between the device and the endoscope makes it difficult to effect incremental movements of the remote tip. In other words, the torque tends to build along the device until resistance due to static friction is overcome, at which point the relative smaller resistance due to kinetic friction allows the torque to be released essentially all at once, thereby causing whipping of the distal portion of the device. Thus, a need remains for an endoscopic probe that is easy to operate and effective in use.